Associações direta e indireta da atividade física e ângulo de fase em adolescentes vivendo com HIV: papel moderador da aptidão física

Abstract

Introduction: HIV infection and combination antiretroviral therapy (ART) may lead to metabolic and cardiovascular alterations in adolescents. Evidence suggests that these individuals have limited habitual physical activity, which may worsen health outcomes. However, there is a need to understand the role of aerobic and muscular fitness, as well as body composition. Objective: To assess the relationship between physical activity levels and phase angle (PhA) and to investigate the mediating and moderating effects of physical fitness on this relationship in adolescents living with HIV. Method: This was an observational, cross-sectional study conducted with adolescents (aged 10 to 18 years) diagnosed with HIV and receiving care at a referral hospital in Maceió-AL, Brazil. Physical activity was assessed using the PAQ-C questionnaire, and PhA was calculated based on resistance and reactance obtained through tetrapolar bioelectrical impedance analysis. Aerobic fitness, muscle strength, and body composition variables (Muscle Cross-Seccional Area [MCSA] and body fat percentage) were assessed through a submaximal step test, handgrip strength test, and anthropometric measurements, respectively. Data were analyzed using linear correlation analyses, simple and multivariate linear regressions, and mediation and moderation analyses, with significance set at p<0.05. Results: A total of 47 adolescents participated (mean age: 14.4 ± 2.2 years), with 25 (53.2%) being female. Of the total, 29 (61.7%) had inadequate PhA values (<5.0º), with a higher prevalence among females (n = 19; 65.5%). A correlation was observed between physical activity scores and PhA (r = 0.39; p = 0.01), even in models adjusted for sex, age, sexual maturation, viral load, CD4+ T lymphocytes, and type of cART (β = 1.087; p = 0.001). When stratified by sex, the adjusted models showed significance in both females (β = 0.645; p = 0.022) and males (β = 1.627; p = 0.005). In the moderation analysis, physical fitness variables did not significantly influence the relationship. However, considering conditional effects, high levels of muscle strength showed a significant effect on the relationship between physical activity levels and PhA (β = 1.0537; p = 0.0024). VO2 Peak had significant effects in the low (β = 0.6153; p = 0.0428), intermediate (β = 0.7847; p = 0.0022), and high (β = 0.9913; p = 0.0039) aerobic fitness strata. Body fat percentage showed significant effects in very low (β = 0.7304; p = 0.0391), intermediate (β = 0.7557; p = 0.0073), and high (β = 0.8032; p = 0.0229) strata, while AMA had significant effects in intermediate (β = 0.7186; p = 0.0065) and high (β = 1.0488; p = 0.0052) strata. Conclusion: There is a direct and significant association between physical activity and PhA, independent of confounding factors. In adolescents living with HIV, aerobic and muscular fitness, as well as body composition (body fat percentage and AMA), partially moderate the relationship between physical activity and PhA through their conditional effects.